1. Field of the Invention
This invention is generally related to rotary fans of the ceiling type which are used for creating an air flow within a room or other area and particularly to supplemental blades or blade attachments which are selectively mounted to the main or primary blades of conventional ceiling fans. The blade attachments are continuously curved along their length and are mounted to the primary fan blades in such a manner that a turbulent air flow is created in a zone which is spaced radially outwardly with respect to the normal downdraft of air created by the fan. Although the blade attachments may be integrally formed with the primary fan blades, in the preferred embodiment of the invention, the blade attachments are removably or detachably mounted to the end portions of existing ceiling fan blades by use of clamping members which are adaptable to a plurality of blade sizes and configurations.
2. History of the Invention
Conventional ceiling fans are utilized to create an air turbulence or movement of air within an enclosed area and thereby provide a more comfortable environment. The air turbulence created by such fans not only serves to circulate the air within a given enclosure or area thereby dispersing smoke, odors and the like, but also, such air movement creates a cooling effect by increasing the convective heat exchange rate with respect to people within the areas. Because of the foregoing benefits and as ceiling fans are quiet and inexpensive to operate, there has been a recent increase in the demand for such products either as alternatives for high cost refrigerated air conditioning or as supplements thereto.
Ceiling fans normally have rather large blades which are mounted to a motor so as to be rotated in a horizontal plane at relatively low revolutions per minute. As the fan blades are rotated, a downdraft of air is created with the air above the blades being forced downwardly toward the floor of a room or enclosure. A flow or pattern of air movement is created by the fans which may be considered somewhat toroidal in configuration or circular in cross section. Such a flow, therefore, creates or leaves zones of air which are not subjected to the air turbulence. Such air zones or pockets of non-turbulent air are generally located in spaces which are oriented radially outwardly with respect to the column or downdraft of air which is created by the rotation of the fans. Further, although the pitch of the fan blades may be varied or changed, such modifications have not been totally satisfactory in creating increased air dispensing nor are such solutions to increasing air turbulence applicable to existing fan structures.
In the past, there have been a number of attachments designed for use with electric fan blades and blades for ceiling fans. In U.S. Pat. No. 871,729 to McChord, Jr., one type of supplemental ceiling fan blade attachment is suggested as being adjustably mounted to the ends of the ceiling fan blades. The supplemental blades, however, are relatively large and rectangular in configuration thereby providing or creating a large air resisting surface which would not only place an undesirable load on the fan motor but which would create noise as the supplemental blades are rotated. Further, the supplemental blades are mounted or attached to the main blades by bulky adjustable clamps which would require that each supplemental blade be perfectly adjusted in a like manner with respect to the fan blades in order not to adversely effect the rotational balance of the fan. Such a structure, therefore, would not provide for a balanced load on a fan and would not insure that turbulent air is created in the areas which are angularly offset from the downdraft space without the creation of unacceptably large resistances to the rotation of the fan and by creating increased loads and vibratory stresses.